Articles
EFFECT OF DIFFERENT O2 LEVELS ON SPINACH (SPINACIA OLERACEA L.) GROWN IN A FLOATING SYSTEM
Article number
614_94
Pages
631 – 637
Language
English
Abstract
A study was carried out to evaluate the effect of different oxygen levels in the nutrient solution on spinach grown in a floating system in summer or autumn period.
Two methods were utilized to supply oxygen to the nutrient solution, based respectively on circulating water and insufflating air, and compared to a control treatment, with no oxygenation.
In autumn oxygen level was higher, related to the lower temperature of the nutrient solution.
However, in both periods it tended to decrease during cultivation, reaching the lowest values (less than 2 mg L-1) in the control, and maintaining the highest ones (always higher than 5 mg L-1, even in summer) in insufflating air system.
In the summer period, when the temperature of the nutrient solution ranged between 23 and 29°C, the effect of the different oxygen concentrations on plant growth was evident especially for leaf fresh and dry weight, leaf length, root fresh weight and root length, with statistically significant differences between the three treatments.
The higher values were obtained with insufflating air system.
For SPAD, leaf number, leaf area and root dry weight, only the control differed significantly from both the oxygenated treatments.
In the autumn period, with temperature of the nutrient solution ranging from 13 to 24°C, although some differences between treatments were noticed, they were less evident and statistically not significant except for root length, that was lower in the plants grown without oxygenation.
However, plant growth was much lower than in summer.
These results indicate that supplying oxygen to the nutrient solution is very important for spinach grown in a floating system, mainly in the summer period, when oxygen level reaches lower values and plants grow rapidly.
Between circulating water and insufflating air, the latter method appeared to be more effective.
Two methods were utilized to supply oxygen to the nutrient solution, based respectively on circulating water and insufflating air, and compared to a control treatment, with no oxygenation.
In autumn oxygen level was higher, related to the lower temperature of the nutrient solution.
However, in both periods it tended to decrease during cultivation, reaching the lowest values (less than 2 mg L-1) in the control, and maintaining the highest ones (always higher than 5 mg L-1, even in summer) in insufflating air system.
In the summer period, when the temperature of the nutrient solution ranged between 23 and 29°C, the effect of the different oxygen concentrations on plant growth was evident especially for leaf fresh and dry weight, leaf length, root fresh weight and root length, with statistically significant differences between the three treatments.
The higher values were obtained with insufflating air system.
For SPAD, leaf number, leaf area and root dry weight, only the control differed significantly from both the oxygenated treatments.
In the autumn period, with temperature of the nutrient solution ranging from 13 to 24°C, although some differences between treatments were noticed, they were less evident and statistically not significant except for root length, that was lower in the plants grown without oxygenation.
However, plant growth was much lower than in summer.
These results indicate that supplying oxygen to the nutrient solution is very important for spinach grown in a floating system, mainly in the summer period, when oxygen level reaches lower values and plants grow rapidly.
Between circulating water and insufflating air, the latter method appeared to be more effective.
Publication
Authors
R. Tesi, A. Lenzi, P. Lombardi
Keywords
hydroponics, hypoxia, nutrient solution, temperature, Spinacia oleracea
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